Associate an object with Marker (google map v2)

Question

In my app I have some objects that have their location displayed on the map using markers. The problem is that the only way I've found to handle marker clicks is

googleMap.setOnMarkerClickListener(new ... {
    @Override
    public void onMarkerClick(Marker marker) {
       // how to get the object associated to marker???
    }
})

In other words I get the Marker object while the only interface that I have allows me to set just MarkerOptions.

Any way to associate Marker with an object?

Budius · Answer 1 · 2012-12-27T12:28:12.580

54

I reckon this callback was not very thoroughly though by the Android team, but, it's what we have.

Whenever you call mMap.addMarker(); it returns the generated marker. You can then use a HashMap or some other data holder structure to remember it.

// Create the hash map on the beginning
WeakHashMap <Marker, Object> haspMap = new WeakHashMap <Marker, Object>();


// whenever adding your marker
Marker m = mMap.addMarker(new MarkerOptions().position(lat, lng).title("Hello World").icon(icon_bmp));
haspMap.put(m, your_data);

edited Dec 27 '12 at 12:28

answered Dec 27 '12 at 12:03

Budius

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I recommend `WeakHashMap`, so when a `Marker` gets garbage-collected, so will its associated `WeakHashMap` entry and `Object` value. But, yes, unfortunately this seems to be the only option at present. – CommonsWare Dec 27 '12 at 12:25
1

makes sense to me. I edited my answer to be WeakHashMap. Is that ok? – Budius Dec 27 '12 at 12:28
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bzzzzt, wrong! I had to use an HashMap, otherwise the mapping gets somehow garbage collected. – dwery Aug 31 '13 at 01:57
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The documentation says that marker object may change, so don't use the marker as the key, use m.getId(). – dwery Aug 31 '13 at 02:05
hi @dwery , I can't find that on the documentation. Could you point to a link, please? – Budius Dec 18 '13 at 10:50
@dwery If you do so, you have no chance to remove the marker because you don't have the reference. – DarkLeafyGreen Sep 24 '14 at 11:35
@CommonsWare unless you use this WeakHashMap throughout the app it is not useful for this purpose. – Rafael Nov 16 '16 at 14:04

score 36 · Accepted Answer · answered Aug 24 '16 at 11:51

36

You can associate arbitrary object by using Marker's setTag() method

Marker amarker = mMap.addMarker(new MarkerOptions().position(lat, lng).title("Hello World"));
amarker.setTag(new SomeData());

To retrieve data associated with marker, you simply read it using its getTag() and then cast it to its original type.

SomeData adata = (SomeData) amarker.getTag();

More information

answered Aug 24 '16 at 11:51

Zamrony P. Juhara

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This is the correct solution. As per documentation about Tag in Marker : "An Object associated with the marker. For example, the Object can contain data about what the marker represents. This is easier than storing a separate Map. " – JDenais Sep 30 '16 at 09:10
Correct solution as of Play Services 9.4 – hibob Oct 11 '16 at 09:34
This is the RIGHT solution! – rakesh kashyap Nov 15 '16 at 11:31
That's great that after 4 years they've implemented this out-of-the-box =) – leshka Nov 29 '16 at 18:42

score 8 · Answer 3 · edited May 23 '17 at 11:54

8

Another option would be to create a Map whose keys is marker.getId() and the value is our object.

In this way, we wouldn't keep a reference to a Marker in memory, and wouldn't have to worry about garbage collected markers.

Here you can see more answers.

edited May 23 '17 at 11:54

Community

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answered Nov 21 '13 at 16:23

Sanete

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Associate an object with Marker (google map v2)

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